Voc-free, low viscosity, led-curable coating and method of application

ABSTRACT

This invention is related to compositions that can be used to protect surfaces, such as those found on bowling lanes (both synthetic and wood). The compositions are low viscosity and contain little to no VOCs (volatile organic compounds). In one embodiment, the flowable compositions are 100% solids, while in another embodiment, they are solvent-borne compositions that only include VOC-exempt solvents. Regardless of the embodiment, the compositions can be cured via UV LED light to yield scratch, abrasion, and impact resistant coatings.

RELATED APPLICATIONS

The present application claims the priority benefit of U.S. ProvisionalPatent Application Ser. No. 61/601,353, filed Feb. 21, 2012, entitledVOC-FREE LOW VISCOSITY LED CURABLE COATING AND METHOD OF APPLICATION,incorporated by reference in its entirety herein.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention is broadly concerned with VOC-free protectivecoatings that can be used to protect surfaces, such as those on bowlinglanes.

2. Description of the Prior Art

Protective coatings are utilized in many products, including furniture,appliances and other electrical devices, floors, automotive exteriorpaint, and automotive interior parts. The coating usually protectsplastic, metal, and wooden surfaces from being scratched as well as fromother damage. The coating also conceals some of the underlying surfaceimperfections, makes the surface look smoother, and gives a glossier ormore matte finish depending on the desired final product look.

Many types of coatings have been developed over the years, includingtwo-part, ambient cure, and radiation curable types. A two-part is acoating that must be mixed with a hardener in order to be cured. Anambient cure coating is a coating where either solvent evaporation ormoisture solidifies the coating. Radiation curable coatings include bothultraviolet (UV) light and electron beam (EB) curable coatings and cureby initiating reactions via irradiation. UV light is an electromagneticradiation with a wavelength shorter than visible light wavelength. Whenthe term UV light is applied to radiation curable conventional coatings,the wavelength of UV light is in the region of 100 nm through 400 nm.

Since their development, radiation curable coatings have gainedacceptance due to their almost immediate cure or very short cure times,minimal oven use, and ability to be applied onto thermally unstablesubstrates. In order to cure common radiation curable coatings, UVmercury vapor lamps, which can be arc or microwave powered, areutilized. These lamps emit radiation in UVA, UVB, and UVC regions of theelectromagnetic spectrum. This radiation is useful in the coating cureprocess. Besides UV radiation, these lamps produce a large quantities ofinfrared (IR) radiation (heat) as well as ozone.

A new field in radiation cured coatings that is emerging now is lightemitting diode (LED) curable coatings. There are many advantages tousing LED light sources over conventional UV mercury lamps. Some of theimportant advantages include that LEDs require much less power to run,they are instant on/off light sources, and there is no need for bulkycooling systems. In addition, LEDs have a much longer life compared tomercury vapor lamps. Moreover, current commercially available UV LEDsgenerate neither ozone nor excessive heat that may damage the coatingbeing cured. Current commercially used UV LEDs emit radiation in theclose to visible part of UVA (320-400 nm) and visible portion (400-700nm) of the spectrum.

High energy UV radiation such as UVC (100-290 nm) is required toeffectively cure standard UV coatings that react through free radicalmechanisms such as various acrylate coatings in ambient conditions.Ambient conditions herein are defined as the presence of oxygen atconcentrations that are equal to or above 20% by volume, which can betranslated into 18 kPa oxygen partial pressure. In these conditions,most of the existing free-radical UV curable coating will not besufficiently cured under UVA LED light even if UVA absorbing initiatorsare applied. The surface of the coating does not completely cure, i.e.,it remains tacky after UVA exposure due to oxygen inhibition. Thepractice to apply a nitrogen blanket in order to properly cure these UVcoating compositions is customary even when mercury vapor UV lamps areutilized. This is true especially if high scratch or abrasion resistanceis required.

Coatings that cure through a cationic polymerization route such as thosebearing epoxy functionality do not have the downside of theaforementioned property. Most of the commercially available cationicphotoinitiators do not efficiently absorb light in UVA region. Theaddition of a UVA photosensitizer solves that problem. Therefore, thedevelopment of UV LED epoxy coatings looks like a promising path.Unfortunately, the shortcomings of this route include theyellow/brownish color of the resulting UV-cured epoxy coating, andreduced selection (if compared to available free radical) of lowmolecular weight highly crosslinkable monomers that are not viscous inorder to formulate a 100% solids coating. The Environmental protectionagency (EPA) VOC regulations are getting more strict each year,especially for indoor coatings and finishes. Therefore, the need existsfor a 100% solids or water-based coating that can be cured in ambientconditions with UV LED light.

SUMMARY OF THE INVENTION

The present provides a flowable composition useful for treating asurface. The flowable composition is selected from the group consistingof:

-   -   (1) a metal oxide composition comprising:        -   silica nanoparticles, alumina nanoparticles, or both;        -   an acrylate; and        -   a photoinitiator;    -   (2) a hybrid composition comprising free radical polymerizable        monomers, cationic polymerizable monomers, and a photoinitiator;        and    -   (3) a polymeric composition comprising a polymer and a        photoinitiator dissolved or dispersed in a solvent system, said        polymer being selected from the group consisting of epoxies,        polyurethanes, acrylates, and mixtures thereof.        The flowable composition has a viscosity of less than about 200        cP, comprises less than about 5% by weight volatile organic        compounds, and is curable by light having a wavelength of from        about 320 nm to about 700 nm, and more preferably curable by an        LED light source.

The invention is further concerned with a method of forming a coating ona surface. The method involves applying the above flowable compositionto the surface. The layer is then exposed to light having a wavelengthof from about 320 nm to about 700 nm to form the coating, and moreparticularly to light from an LED light source.

In a further embodiment, the invention provides a protected surface,which comprises a cured coating on the surface to be protected. Thecured coating is formed from the above flowable composition.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

In more detail, the flowable composition is provided in threeembodiments. In the first embodiment, the flowable composition is ametal oxide-containing composition, and it comprises silica and/oralumina nanoparticles, an acrylate (or multiple different types ofacrylates), and a photoinitiator. This embodiment is preferably mostlyor entirely solids. That is, the composition comprises at least about95% by weight solids, preferably at least about 98% by weight solids,and more preferably about 100% by weight solids, based upon the totalweight of the composition taken as 100% by weight.

Suitable silica and alumina nanoparticles include any commerciallyavailable ones, with some specific ones shown in the Examples below.(The Examples also include exemplary commercial products for the othercomponents of this embodiment and the other embodiments as well.) Thenanoparticles preferably have a particle size of from about 10 nm toabout 800 nm, and preferably from about 20 nm to about 250 nm, and aretypically provided dispersed in epoxy monomers, acrylate monomers orresins, and a solvent at a level of from about 1% to about 50% byweight. The silica and/or alumina nanoparticles are present in theoverall composition at levels of from about 1% by weight to about 50% byweight, preferably from about 2% by weight to about 45% by weight, andmore preferably from about 25% by weight to about 45% by weight, basedupon the total weight of the composition taken as 100% by weight.

Suitable acrylates and other free radical polymerizable monomers(“FRPM”) include those selected from the group consisting of aliphaticurethane acrylates, epoxy acrylates, melamine acrylates, monofunctionalacrylates, methacrylates, ethylenically unsaturated monomers and resins,and multifunctional acrylates (difunctional acrylates). Particularlypreferred acrylates are selected from the group consisting of acrylateesters, trimethylol propane triacrylate, 1,6-hexanediol acrylate,1,6-hexanediol diacrylate, isobornyl acrylate, hexafunctional urethaneacrylate, hexafunctional epoxy acrylate, tripropylene glycol diacrylate,epoxy novolak acrylate, ethoxylated trimethylolpropane triacrylate,pentaerythritol triacrylate, dipentaerythritol pentaacrylate, melamineacrylate, propoxylated neopentyl glycol diacrylate, and mixturesthereof.

The acrylates are present in the composition at levels of from about 20%by weight to about 80% by weight, preferably from about 30% by weight toabout 70% by weight, and more preferably from about 45% by weight toabout 65% by weight, based upon the total weight of the compositiontaken as 100% by weight.

Suitable photoinitiators include those selected from the groupconsisting of 2,4,6-trimethylbenzoyldiphenylphosphine oxide, his(2,4,6-trimethylbenzoyl)-phenylphosphineoxide, 4-thiophenyl phenyldiphenyl sulfonium hexafluoroantimonate,2-methyl-1-[4-(methylthio)-phenyl]-2-(4-morpholinyl)-1-propanone, otherphosphine oxide-based photoinitiators, and mixtures thereof. Thephotoinitiators are present in the composition at levels of from about1% by weight to about 10% by weight, preferably from about 2% by weightto about 8% by weight, and more preferably from about 3% by weight toabout 7% by weight, based upon the total weight of the composition takenas 100% by weight.

In another embodiment, the flowable composition is a hybrid compositioncomprising both FRPMs such as acrylates, methacrylates, ethylenicallyunsaturated compounds, and mixtures thereof; and cationic polymerizablemonomers (CPMs) such as epoxies, vinyl ethers, oxiranes, oxetanes,polyols, and mixture thereof. The hybrid composition also comprises aphotoinitiator. Even more preferably, the hybrid composition comprisesat least two photoinitiators: one for initiating free radicalpolymerization and one for initiating cationic polymerization.

The FRPMs are present in the composition at levels of from about 5% byweight to about 95% by weight, preferably from about 10% by weight toabout 80% by weight, and more preferably from about 50% by weight toabout 70% by weight, based upon the total weight of the compositiontaken as 100% by weight. The CPMs are present in the composition atlevels of from about 5% by weight to about 95% by weight, preferablyfrom about 10% by weight to about 80% by weight, and more preferablyfrom about 35% by weight to about 75% by weight, based upon the totalweight of the composition taken as 100% by weight. The totalphotoinitiator is preferably the same as those discussed above withrespect to the metal oxide composition. The free radical photoinitiatoris present in the composition at levels of from about 1% by weight toabout 10% by weight, preferably from about 2% by weight to about 8% byweight, and more preferably from about 3% by weight to about 7% byweight, while the cationic photoinitiator is present in the compositionat levels of from about 1% by weight to about 10% by weight, preferablyfrom about 2% by weight to about 8% by weight, and more preferably fromabout 3% by weight to about 7% by weight, based upon the total weight ofthe composition taken as 100% by weight. Preferred cationicphotoinitiators include those selected from the group consisting ofdyaryliodonium, triarylsulfonium, triarylsulfoxonium,dialkylhydroxyphenylsulfonium, ferrocenium salts, and diazonium salts.

This hybrid embodiment preferably also comprises a VOC-exempt solvent.As used herein, a VOC compound or solvent means one of carbon (excludingcarbon monoxide, carbon dioxide, carbonic acid, metallic carbides orcarbonates, and ammonium carbonate) that participates in atmosphericphotochemical reactions. VOC-exempt solvents are those that havenegligible or no photochemical activity and are defined in 40 C.F.R.51.100(s)(1), incorporated by reference herein. Preferred VOC-exemptsolvents for use in the present invention include those selected fromthe group consisting of dimethyl carbonate, acetone, methyl acetate,p-chlorobenzotrifluoride, propylene carbonate, t-butyl acetate, andmixtures thereof. When a VOC-exempt solvent is utilized, it ispreferably present at levels of from about 10% by weight to about 30% byweight, more preferably from about 12% by weight to about 25% by weight,and even more preferably from about 15% by weight to about 20% byweight, based upon the total weight of the composition taken as 100% byweight. The hybrid composition can also comprise silica or aluminananoparticles in the sizes and quantities discussed above with respectto the metal oxide composition.

In the third embodiment, the flowable composition is a polymericcomposition comprising a polymer or oligomer and a photoinitiatordissolved or dispersed in a solvent system, with the polymer beingselected from the group consisting of epoxies, polyurethanes, acrylates,and mixtures thereof. In this embodiment, the polymer or oligomer ispresent at levels of from about 60% by weight to about 95% by weight,preferably from about 50% by weight to about 80% by weight, and morepreferably from about 60% by weight to about 75% by weight, based uponthe total weight of the composition taken as 100% by weight. Thephotoinitiator is present at levels that are the same as those discussedabove with respect to the metal oxide composition, with the preferredphotoinitiator being a sulfonium or diazonium salt. In this embodiment,the solvent system comprises only VOC-exempt solvents such as thoselisted above, and in the same quantities as in the hybrid embodiment ofthe composition. The polymeric composition can also comprise silica oralumina nanoparticles in the sizes and quantities discussed above withrespect to the metal oxide composition.

In instances where the polymeric composition comprises a polyurethane,water is typically included as a solvent. In such cases, the water ispresent at levels of from about 5% by weight to about 80% by weight,preferably from about 10% by weight to about 60% by weight, and morepreferably from about 30% by weight to about 50% by weight, based uponthe total weight of the composition taken as 100% by weight.

Regardless of which of the three embodiments above are utilized, theycan be provided as thiol-containing or thiol-free. In the former, asource of thiols is included in the composition, with the thiols beinguseful as an oxygen scavenger, thus preventing the oxygen frominhibiting polymerization within the composition. Suitable sources ofthiols include those selected from the group consisting ofpentaerythritol tetra-(3-mercaptopropionate), trimethylolpropanetri-(3-mercaptopropionate), glycol di-(3-mercaptopropionate),pentaerythritol tetramercaptoacetate, trimethylolpropanetrimercaptoacetate, glycol dimercaptoacetate, ethoxylatedtrimethylpropane tri (3-mercapto-propionate), and propylene glycol3-mercaptopropionate.

In such instances, the source of thiols is preferably included insufficient amounts to provide from about 1% by weight to about 10% byweight thiols, preferably from about 2% by weight to about 8% by weightthiols, and more preferably from about 3% by weight to about 5% byweight thiols, based upon the total weight of the composition taken as100% by weight. In the thiol-free aspects, the flowable composition isessentially free of thiols. That is, the flowable composition comprisesless than about 1% by weight thiols, preferably less than about 0.1% byweight thiols, and more preferably about 0% by weight thiols, based uponthe total weight of the composition taken as 100% by weight.

The flowable compositions can also include various optional ingredients.Such ingredients include those selected from the group consisting ofadhesion promoters, leveling agents, metal oxides, waxes, surfactants,photosensitizers, antifoaming agent, oxygen inhibition offsettingadditives, and mixtures of the foregoing. When utilized, they arepresent in the following amounts:

INGREDIENT BROADEST^(A) PREFERRED^(A) adhesion promoter about 0 to about5% about 0.1 to about 1% leveling agents about 0.01 to about 3% about0.04 to about 0.8% metal oxides about 0.01 to about 50% about 2 to about45% waxes about 0 to about 5% about 0.05 to about 2% surfactants about0.01 to about 3% about 0.05 to about 0.6% photosensitizers^(B) about 1to about 10% about 2 to about 5% antifoaming agent about 0.01 to about3% about 0.05 to about 0.7% oxygen inhibition about 1 to about 10% about0.1 to about 5% offsetting additives^(C) ^(A)based upon the total weightof the composition taken as 100% by weight. ^(B)Such as anthracene,thioxanthone, naphthalene, perylene, pyrene, or phenothiazine. ^(C)Suchas multifunctional mercapto compounds (e.g., polythiols) oramino-containing compounds such as aminofunctional acrylates.

Furthermore, regardless of the embodiment, the flowable composition hasa low viscosity. That is, the composition will have a viscosity of lessthan about 500 cP, preferably less than about 400 cP, more preferablyless than about 200 cP, and even more preferably from about 1 cP toabout 200 cP. As used herein, viscosity is determined by a BrookfieldLVDV+II Pro Viscometer at 22° C.

Additionally, while the flowable composition may or may not comprise aVOC-exempt solvent, as discussed above, it will comprise little to noVOCs. That is, the composition will preferably comprise less than about5% by weight VOCs, more preferably less than about 1% by weight VOCs,and even more preferably about 0% by weight VOCs, based upon the totalweight of the composition taken as 100% by weight.

Finally, in another embodiment, the composition is free of amines. Thatis, the composition will comprise less than about 5% by weight aminegroups, preferably less than about 1% by weight amine groups, and morepreferably about 0% by weight amine groups, based upon the total weightof the composition taken as 100% by weight.

In use, the flowable composition is applied to the particular surface tobe protected by any conventional application method. For example, thecomposition can be sprayed onto the surface, brushed onto the surface,or pulled with a squeegee. Other suitable methods include dip-coating,silk-screening, and application with a roller. The composition can beapplied directly to the surface, or to a primer layer (e.g., adhesionpromoting layer) on the surface. Typical surfaces that might beprotected with the inventive coatings include those selected from thegroup consisting of high pressure decorative laminate surface (such as asynthetic bowling lane surface) as well as wooden and plastic surfaces.Specific additional examples include vinyl composite tile flooring,hardwood flooring, and laminate flooring.

Once a layer of the composition is applied to the surface, it is exposedto UV LED light. That is, the layer is exposed to light having awavelength of from about 320 nm to about 700 nm, preferably from about350 nm to about 500 nm, and more preferably from about 365 nm to about420 nm, to form a cured coating. Any commercially available orcustom-made UV LEDs can be used. Powerful UV LEDs are available from thecompanies such as Phoseon Technology (Hillsboro, Oreg.), HamamatsuCorporation (Bridgewater, N.J.), UV Process Supply, Inc. (Chicago, Il),Clearstone Technologies Inc. (Minneapolis, Minn.), Heraeus NoblelightLLC (Buford, Ga.), and LEDs Masters (Guangdong China (Mainland)). Insome embodiments, the light source could be one selected from the groupconsisting of xenon lamps, helium lamps, and some low-energy mercurylamps.

The light exposure activates the photoinitiator, causing polymerizationto occur in embodiments where polymerizable monomers are present. Thepolymers will preferably also crosslink during this process, whetherthey are polymers that were newly formed during light exposure, orwhether they were added as polymers when preparing the composition(e.g., in the polyurethane embodiments). This curing process will resultin a coating having an average thickness (an average taken over 5measurements) of from about 2 μm to about 200 μm, and more preferablyfrom about 3 μm to about 100 μm. It will be appreciated that the presentinvention provides significant benefits over the prior art in that theinventive compositions cure successfully in the presence of oxygen inambient conditions without partial or complete inert gas (nitrogen,carbon dioxide) blanketing.

Advantageously, the cured coating will have a number of desirableproperties. For example, when subjected to an abrasion test as definedherein, the coatings will have a AHaze of less than about 30, preferablyless than about 20, and more preferably from about 0 to about 10. Theywill also have a coefficient of friction of less than about 0.8,preferably less than about 0.29, and more preferably from about 0.08 toabout 0.20.

The coatings will also have an adhesion of at least about 90%,preferably at least about 95%, and more preferably about 100%. Theimpact resistance of the coatings will be at least about 140 inch-lb,preferably at least about 150 inch-lb, and more preferably at leastabout 160 inch-lb. Finally, the Sward hardness of the coating will befrom about 30 to about 55, and preferably from about 35 to about 50.

EXAMPLES

The following examples set forth preferred methods in accordance withthe invention. It is to be understood, however, that these examples areprovided by way of illustration and nothing therein should be taken as alimitation upon the overall scope of the invention.

Testing Procedures 1. Abrasion

A sample of the particular mixed coating was applied to a polyethyleneterephthalate (PET) film using differently sized wire rods. The coatingwas cured with a UV LED light source: 4 W/cm² 395 nm air cooled RXFirefly light source from Phoseon Technology (Hillsboro, Oreg.). Curingtook place at a speed of 10 fpm at a distance of 5 mm from the LEDsurface.

Abrasion was tested with a TABER® Rotary Platform Abrasion Tester. Thecoating was subjected to a 100 cycles with 500 g load and CS-10F wheels.Haze of the coating was determined before and after the abrasion, andthe change in haze (AHaze) was recorded.

2. Scratch

Samples were prepared exactly as described in Part 1 above for theAbrasion test. The Scratch test was performed with a 000 steel wool, 20rubs with no weight applied. The results were inspected visually.

3. Adhesion

Samples were prepared exactly as described in Part 1 above for theAbrasion test, except that the coating was applied to a syntheticbowling lane. Adhesion was tested by the method described in ASTMDD3359.

4. Impact Resistance

Samples were prepared exactly as described in Part 1 above for theAbrasion test, except that the coating was applied to a syntheticbowling lane. Impact Resistance was tested with a Taber Heavy DutyImpact Tester by following ASTM D2794, D3029, and D4226.

5. Coefficient of Friction

Samples were prepared exactly as described in Part 1 above for theAbrasion test, except that the coating was applied to a syntheticbowling lane. The Coefficient of Friction was then tested according thetest specified for synthetic bowling lane surface in the USBC manual.This method was designed for determining the coefficient of friction ofa bowling lane surface using a weighted sled with urethane feet. In themethod, the force needed to slide a sled with a total weight of 14pounds across a coated synthetic lane surface at a speed of about 0.5feet per second was measured. The lane sample was cleaned thoroughlywith isopropyl alcohol and allowed to dry completely. The sample wasthen pre-treated by applying a heavy layer of lane conditioner andallowed to saturate for a total of 72 hours. The sample was then cleanedthoroughly with isopropyl alcohol to remove all lane conditioner fromthe surface of the sample. Next, the force was measured. The resultingforce was then divided by 14 lb weigh to calculate the kineticcoefficient of friction.

6. Sward Hardness

Sward hardness is the surface hardness of a material measured by arocker device such as Gardner/Sward Hardness Rocker. The hardness valuewas obtained from the damping of the oscillation of the rocker, which isproportional to the hardness of the material.

The sward hardness rocker was placed on a flat, completely dry andclean, leveled synthetic lane surface sample. The instrument was rotatedto between 25 to 27 degrees from its “at rest” position, and then therocker was released. As soon as the swing amplitude decayed to the highset limit of approximately 22 degrees, the counter automatically startedregistering each swing cycle and continued to do so until the swingamplitude dropped below the low set limit of approximately 16 degrees.The average of the several readings multiplied by 2 gave the hardnessvalue.

Coating Formulation Preparation

In each instance, the components of the coating composition were mixedin ambient conditions with light exposure kept to a minimum.Polyethylene containers were used for mixing, which was accomplishedwith a laboratory mixer equipped with a stainless steel blade. Thefollowing Examples and accompanying tables set forth the variousformulations that were tested.

Example 1 100% Solids UV LED Curable Formulation with Thiols Example 1.1

WEIGHT COMPONENT % Nanocryl C-145 (50 wt. % silica nanoparticles intripropylene 68.1 glycol diacrylate, Nanophase Technologies, Romeoville,IL) Sartomer CD 595 (acrylate ester, Sartomer USA, LLC, Exton, 17 PA)TEGO Flow 370 (acrylate-based flow/leveling agent, Evonik 0.6 TegoChemie GmbH, Essen Germany) Sartomer CD9053 (adhesion promoter,trifunctional acid ester, 4.3 Sartomer USA) Thiocure TMPMP(trimethylolpropane tri-3-mercaptopropio- 4.3 nate, Evans ChemeticsInc., Waterloo, NY) Chivacure TPO(2,4,6-trimethylbenzoyldiphenylphosphine 2.8 oxide; photoinitiator,Chitec Technologies, Taiwan) Irgacure 819 (bis(2,4,6-trimethylbenzoyl)-phenylphosphine- 2.8 oxide; photoinitiator,BASF) Effka 3883 (a polysiloxane modified-polymer terminated by 0.1unsaturated groups; leveling agent, BASF)

Example 1.2

WEIGHT COMPONENT % Nanocryl C-145 67.5 SR 306F (tripropylene glycoldiacrylate, Sartomer) 17.0 Irgacure 819 4.1 Darocur TPO(2,4,6-trimethylbenzoyldiphenylphosphine 1.4 oxide; photoinitiator,BASF) Thiocure TMPMP 4.75 Sartomer CD9053 4.5 TEGO Flow 370 0.75

Example 1.3

WEIGHT COMPONENT % Nanocryl C-140 (50 wt. % silica in difunctionalacrylate 67.0 monomers, Evonik, Germany) SR 306F 17.5 Irgacure 819 4.1Darocure TPO 1.4 Thiocure TMPMP 4.75 Sartomer CD9053 4.5 TEGO Flow 3700.75

Example 1.4

WEIGHT COMPONENT % Nanocryl C-145 68.6 Irgacure 819 1.4 Darocure TPO 4.1Sartomer CD595 17 Thiocure TMPMP 4.3 Sartomer CD9053 4.3 TEGO Flow 3700.3

Example 1.5

WEIGHT COMPONENT % Nanocryl C-145 64.6 Irgacure 819 1.4 Darocure TPO 4.1Sartomer CD595 17 Thiocure TMPMP 4.3 Sartomer CD9053 4.3 TEGO Flow 3700.3 Aluminum Oxide, 250 nm (55 wt. % Al₂O₃ in tripropylene 4.0 glycoldiacrylate, Nanophase Technologies)

Example 1.6

WEIGHT COMPONENT % Nanocryl C-140 67.8 Darocure TPO 3.5 Irgacure 819 1.1TEGO Flow 370 0.5 Polyfluo 523 XF (polyethylene waxes with PTFE, Micro1.7 Powders, Inc., NY) Sartomer CD9053 4.2 Thiocure TMPMP 4.2 SartomerSR306 17

Example 1.7

WEIGHT COMPONENT % Nanocryl C-140 67.8 Darocure TPO 3.5 Irgacure 819 1.1TEGO Flow 370 0.5 Polyfluo 523 XF 1.7 Sartomer CD9053 4.2 Thiocure TMPMP4.2 SR238 (1,6 hexanediol diacrylate, Sartomer) 17

Example 1.8

WEIGHT COMPONENT % Nanocryl C-140 64.7 Aluminum Oxide, 40 nm (30 wt. %Al₂O₃ in tripropylene 2.5 glycol diacrylate, Nanophase Technologies)Irgacure 819 1.35 Darocure TPO 4 SR 238 17 Thiocure TMPMP 4.2 SartomerCD9053 4.2 Ceridust 5091 (wax; Ester of pentaeryhtrite, motanic acids,1.6 and acrylic acid, Clariant) TEGO Flow 370 0.45

Example 2 100% Solids UV LED Curable Formulation without Thiols Example2.1

WEIGHT COMPONENT % Nanocryl C-140 82.3 Sartomer CD9053 11 Chivacure TPO2.7 Irgacure 819 3.9 Effka 3883 0.1

Example 2.2

WEIGHT COMPONENT % Nanocryl C-153 (50 pbw silica nanoparticles inethoxylated 86 trimethylolpropantriacrylate, Evonik, Germany) SartomerCD9053 10 Irgacure 819 3.8 TEGO Flow 370 0.2

Example 2.3

WEIGHT COMPONENT % Nanocryl C-153 50 Nanocryl C-140 36 Sartomer CD905310 Irgacure 819 3.8 TEGO Flow 370 0.2

Example 3 VOC-Exempt Solvent Diluted Formulation with Thiols Example 3.1

WEIGHT COMPONENT % Sartomer CN 112C60 (epoxy novolak acrylate blendedwith 27.2 40% trimethylolpropane triacrylate, Sartomer) Sartomer SR444(pentaerythritol triacrylate, Sartomer) 13.6 Nanocryl C-150 (50 wt. %silica nanoparticles in trimethylol- 13.6 propane triacrylate, NanophaseTechnologies Sartomer SR399 (dipentaerythritol pentaacrylate, Sartomer)13.6 Sartomer CD9053 3.4 Chivacure TPO 2.2 Irgacure 819 2.2 TEGO Flow370 0.7 Thiocure TMPMP 3.4 BYK UV 3500 (polyether modified acrylfunctional poly- 0.1 dimethylsiloxane, BYK, Germany) VOC-Exempt Solvent(Dimethylcarbonate, from Special 20 Material Company, Lakeworth, FL)

Example 3.2

WEIGHT COMPONENT % CN9890 (melamine acrylate, Sartomer) 20.0 SR 351(trimethylolpropane triacrylate, Sartomer) 16.0 Nanocryl C-150 16.0 SR454 (ethoxylated trimethylolpropane triacrylate, Sartomer) 11.0 SR 9003(propoxylated(2) neopentyl glycol diacrylate, 16.0 Sartomer) Sartomer CD9053 4.0 Thiol 3.4 Darocure TPO 5.3 TEGO Flow 370 0.3 VOC exempt solvent(dimethylcarbonate) 8.0

Example 3.3

WEIGHT COMPONENT % SR 399 (low viscosity dipentaerythritol pentacrylate,21 Sartomer) SR351 16.75 Nanocryl C-150 16.75 SR 454 12.5 SR 9003 8.3Ebecryl P115 (photactivator, copolymerizable amine, 8.3 Cytec, NJ)Darocure TPO 5.8 TEGO Flow 370 0.4 VOC exempt solvent(dimethylcarbonate) 10.2

Example 3.4

WEIGHT COMPONENT % SR 399 20.0 SR351 16.1 Nanocryl C-150 16.1 SR 45412.0 SR 9003 16.1 Irgacure 819 5.1 TEGO Flow 370 0.4 Sartomer CD 9054(trifunctional acid ester) 4.0 VOC Exempt Solvent (dimethylcarbonate)10.2

Example 3.5

WEIGHT COMPONENT % Sartomer CD595 7.6 CN9890 39.3 Nanocryl C-165 (50 pbwsilica nanoparticles in propoxylated 39.3 pentaerythritoletrarylate,Nanocryl) Thiocure TMPMP 4 Sartomer CD9053 4 MASURF FS-2000 (nonionicfluoroaliphatic polymer 0.01 fluorosurfactant, Mason Chemical Company,IL) TEGO Flow 370 0.39 Irgacure 819 1.3 Darocure TPO 4.1

Example 4 VOC-Exempt Solvent Diluted Formulation without Thiols

WEIGHT COMPONENT % Nanocryl C-153 70 Sartomer CD9053 9 Irgacure 819 3.8Acetone 17 TEGO Flow 370 0.2

Example 5 Influence of Thiol Levels on Properties of Cured Coatings

The formulation of Example 3.1 was prepared multiple times, but withvarying amounts of Thiocure TMPMP, so that the impact of thiols on thecoating could be analyzed. See Table A.

TABLE A Solvent-Based UV LED Bowling Lane Finish COEFFICIENT OF ΔHAZE %THIOL^(A) FRICTION SCRATCH^(B) (ABRASION) 0 0.36 4 15.1 0.15 0.34 2-312.9 0.35 0.33 2-3 14.9 0.6 0.33 3 13.2 1.2 0.28 0.5-1   14.6 2.4 0.29  0.25 12.2 3.5 0.305 0 13.5 5 0.35 0 12.4 10 0.36 0 12.8 ^(A)Based uponweight of resins. ^(B)Where 5 is worst, and 0 is best (i.e., noscratches).

Next, the formulation of Example 1.1 was prepared multiple times, butwith varying amounts of Thiocure TMPMP, so that the impact of thiols onthe coating could be analyzed. See Table B.

TABLE B 100% Solids UV LED Bowling Lane Finish COEFFICIENT OF ΔHAZE %THIOL^(A) FRICTION SCRATCH^(B) (ABRASION) 0 0.38 2 8.0 0.5 0.40 0.5 7.81 0.38 0-0.25 8.2 1.5 0.36 0 5.6 2.5 0.35 0 5.9 5 0.39 0 6.0 10 0.40 05.9 ^(A)Based upon weight of resins. ^(B)Where 5 is worst, and 0 is best(i.e., no scratches).

The results from Tables A-B demonstrate that the scratch resistance ofthe coating depends significantly on the amount of the added thiol. Thesolvent-borne formulation required at least 3.5% of thiol in order toachieve sufficient scratch resistance, while a solvent-free formulationrequired only 1.5%.

The impact on abrasion resistance was not as dramatic, but the abrasionresistance continually improved with the increase in thiolconcentration.

There was also an effect on the coefficient of friction by the additionof thiol. The coefficient of friction decreased with lowerconcentrations of thiol until the full cure of the surface of thecoating is achieved. After that, the coefficient of friction increasedwith further increases in thiol concentration.

The presence of thiols can make the formulations unstable since oxygeninhibition of spontaneous polymerization is absent in this case. Atconcentrations of thiol above 10% the formulations tend to become veryunstable. Solvent-free formulations gel almost instantly in theseinstances. The shelf life of the solvent-borne coating formulation ismore than 6 months in a glass container. The shelf life of a 100% solidsformulation depends on its composition, but is generally much shorterthan that of a solvent-borne composition.

Example 6 Hybrid Coating Formulation Example 6.1

WEIGHT COMPONENT % Erisys GE-30 (trimethylolpropane triglycidyl ether,CVC 25.5 Specialty Chemicals) Nanopox C-680(3,3,5,5-tetramethyl-1-pyrolline-N-oxide, 25.5 colloidal silica sols inepoxy resins, Evonik, Germany) Sartomer CN112C60 11 Sartomer SR 399 11Dimethyl Carbonate 22 Irgacure 819 1.5 Aceto 6976 (4-thiophenyl phenyldiphenyl sulfonium 1.5 hexafluoroantimonate; cationic photoinitiator,Aceto Corp, Germany) Chivacure DETX (photosensitizer;2,4-diethylthioxanthone, 1.5 Chitec) TEGO Flow 370 0.4 BYK UV 3500 0.1

Example 6.2

WEIGHT COMPONENT % Erisys GE-30 38.4 Nanopox C-680 33.8 SartomerCN112C60 10.0 Sartomer SR399 10.0 Aceto 6976 3.3 DETX 3.3 Irgacure 8191.2

Example 6.3

WEIGHT COMPONENT % Erisys GE-30 32.5 Nanopox C-680 28.7 SartomerCN112C60 15 Sartomer SR399 16.6 Aceto PI 6976 2.6 DETX 2.6 Irgacure 8192

Example 6.4

WEIGHT COMPONENT % Erisys GE-30 45.5 Beckopox EP 147 (Bisphenol A/Fliquid epoxy resin 19.2 containing crosslinkable emulsifiers, Cytec, NJ)Nanocryl C-150 18.3 Sartomer CN112C60 9 DETX 3 Aceto PI 6976 3 Irgacure819 2

Example 7 Epoxy Formulation Example 7.1

WEIGHT COMPONENT % Erisys GE-30 29 Nanopox C-680 29 Dimethylcarbonate 36Aceto PI 6976 2.8 DETX 2.5 TEGO Flow 370 0.7

Example 7.2

WEIGHT COMPONENT % Erisys GE-30 30.7 Nanopox 680 30.7 VOC-exempt solvent(dimethyl carbonate) 30.7 Aceto PI 6976 3.1 DETX 3.7 TEGO Flow 370 0.47Chartwell 515-71 HR (amino-functional, metal organic 0.6 adhesionpromoter in propylene glycol, Chartwell International, MA) Capstone 62AL(3,3,4,4,5,5,6,6,7,7,8,8,8-tridecafluoro-1- 0.03 octanol, DuPont)

Example 7.3

WEIGHT COMPONENT % Erisys GE-31 (aliphatic trifunctional epoxy diluent;30.8 trimethylolethane triglycidyl ether, CVC Specialty Chemicals)Nanopox 680 30.8 VOC-exempt solvent (dimethyl carbonate) 30.8 Aceto PI6976 3.2 DETX 3.8 TEGO Flow 370 0.6

Example 7.4

WEIGHT COMPONENT % Erisys GE-60 (an aliphatic polyfunctional epoxyresin; 30.8 sorbitol glycidyl ether, CVC Specialty Chemicals) Nanopox680 30.8 VOC-exempt Solvent (dimethyl carbonate) 30.8 Aceto PI 6976 3.2DETX 3.8 TEGO Flow 370 0.6

Example 7.5

WEIGHT COMPONENT % Erisys GE-60 10 Erisys GE-30 10 Erisys GE-31 10Nanopox 680 31.6 VOC-exempt Solvent (dimethyl carbonate) 31 Aceto 69763.1 DETX 3.7 TEGO Flow 370 0.6

Example 8 UV Curable Polyurethane Dispersion Example 8.1

WEIGHT COMPONENT % Bayhydrol UV XP 2689 (anionic polyurethanedispersion, 81 Bayer) DETX (10% in solvent) 12 Irgacure 819WD 2.4Ebecryl P115 0.6 Michem Lube 190 (anionic polyethylene wax emulsion, 4Michelman, OH)

Example 8.2

WEIGHT Component % Ucecoat 7699 (acrylated polyurethane dispersion,Cytec, NJ) 83.4 DETX (10% in solvent) 8 Darocure TPO (10% in solvent) 4Ebecryl P115 0.6 Irgacure 819 4

Example 8.3

WEIGHT Component % Ucecoat 7710 (polyurethane dispersion, Cytec, NJ) 85DETX (10% in solvent) 8 Darocure TPO (10% in solvent) 4 Ebecryl P115 0.6Irgacure 819 4

Example 9 Comparison of the Sward Hardness of the Coating

Table C provides the sward hardness ranges of the coatings from Examples1-5.

TABLE C Coating type Sward Hardness 100% solids, Example 1 40-48Solvent-based, Example 2 40-50 Hybrid coating, Example 6 28-40 Epoxycoating, Example 7 24-42 UV PUD, Example 8 26-40

Example 10 Impact Resistance and Adhesion of Cured Coatings

The impact resistance of Examples 1-4 and 6-7 above were tested aftercoating onto a synthetic bowling lane surface (as described in theTesting Procedures section above), and all were above 160 inch-lb.,which is the highest resistance level than can be measured with theTaber Heavy Duty Impact Tester.

The adhesion of Examples 1-4 and 6-8 above were tested, and all had a95-100% retention of the coating on the test surface.

Example 11 Comparative Examples

The properties and performance of the inventive bowling lane finisheswere compared to synthetic bowling lane surfaces. This surface isoriginally coated with a melamine-formaldehyde resin when manufactured.Melamine-formaldehyde resins are one of the hardest and toughestmaterials, and it is desirable for the inventive coating was to reachthe performance numbers of this original material. A standardEN438/YSO4586 test that is commonly utilized in testing of HPDL surfaceswas used.

S-42 abrasive strips on S0 rubber wheels with 500 g/arm weights wereused in the Taber test. The number of cycles that was needed tocompletely remove the coating was recorded.

SURFACE NUMBER OF CYCLES Edge Approach 14,500 Edge Lane 10,000 BrunswickLane 7,600 Qubica AMF lane 8,000 Example 1: 100% solids coating10,000-16,000

The presented synthetic lane finish performance was compared tocommercially available wood lane coatings as well. Abrasion resistance(the smaller the AHaze, the better the resistance), scratch resistance(0=best . . . 5=worst), and coefficient of friction were assessed asdescribed above. Both wood lane coatings were urethane-based ones.Therefore, their properties were tested at least 10 days after coatingapplication in order to let the material crosslink to full extent andacquire its final properties.

Coefficient of Coating Scratch Friction ΔHaze Brunswick USP 300 4 0.21129.0 Brunswick Astrolane E-Z 4 0.24 34.0 Example 1.1: 100% solid coating0 0.25 5-10

These examples demonstrated that the 100% solids UV LED coatingaccording to the invention surpassed many characteristics ofcommercially available wood lane coatings. Moreover, it achieved theperformance of a very tough synthetic lane surface.

We claim:
 1. A method of forming a coating on a surface, said methodcomprising: providing a flowable composition being selected from thegroup consisting of: (1) a metal oxide composition comprising: silicananoparticles, alumina nanoparticles, or both; an acrylate; and aphotoinitiator; (2) a hybrid composition comprising free radicalpolymerizable monomers, cationic polymerizable monomers, and aphotoinitiator; and (3) a polymeric composition comprising a polymer anda photoinitiator dissolved or dispersed in a solvent system, saidpolymer being selected from the group consisting of epoxies,polyurethanes, acrylates, and mixtures thereof; said flowablecomposition having a viscosity of less than about 200 cP and comprisingless than about 5% by weight volatile organic compounds; applying alayer of said flowable composition to said surface; and exposing saidlayer to light having a wavelength of from about 320 nm to about 700 nmto form said coating.
 2. The method of claim 1, wherein said flowablecomposition further comprises a source of thiols.
 3. The method of claim2, wherein said source of thiols is present at a level of from about 1%by weight to about 10% by weight thiols, based upon the total weight ofthe flowable composition taken as 100% by weight.
 4. The method of claim1, wherein said flowable composition is essentially free of thiols. 5.The method of claim 1, wherein said exposing causes polymerization ofcomponents in said flowable composition.
 6. The method of claim 5,wherein said exposing causes crosslinking of polymers formed during saidpolymerization.
 7. The method of claim 1, wherein said flowablecomposition comprises less than about 1% of volatile organic compounds.8. The method of claim 1, wherein said coating, when subjected to anabrasion test, has a ΔHaze of less than about
 30. 9. The method of claim1, wherein said coating has a coefficient of friction of less than about0.8.
 10. The method of claim 1, wherein said coating has an adhesion ofat least about 90%.
 11. The method of claim 1, wherein said coating hasan impact resistance of at least about 140 inch-lb.
 12. The method ofclaim 1, wherein said acrylate is selected from the group consisting ofacrylate esters, trimethylol propane triacrylate, 1,6-hexanediolacrylate, 1,6-hexanediol diacrylate, isobornyl acrylate, hexafunctionalurethane acrylate, hexafunctional epoxy acrylate, tripropylene glycoldiacrylate, epoxy novolak acrylate, ethoxylated trimethylolpropanetriacrylate, pentaerythritol triacrylate, dipentaerythritolpentaacrylate, melamine acrylate, propoxylated neopentyl glycoldiacrylate, and mixtures thereof.
 13. The method of claim 1, whereinsaid photoinitiator is selected from the group consisting of2,4,6-trimethylbenzoyldiphenylphosphine oxide, his(2,4,6-trimethylbenzoyl)-phenylphosphineoxide, 4-thiophenyl phenyldiphenyl sulfonium hexafluoroantimonate, and mixtures thereof.
 14. Themethod of claim 1, wherein: said free radical polymerizable monomers areselected from the group consisting of acrylates, methacrylates, otherethylenically unsaturated monomers and resins, and mixtures thereof; andsaid cationic polymerizable monomers are selected from the groupconsisting of epoxies, oxetanes, oxiranes, vinyl ethers, and mixturethereof.
 15. The method of claim 1, wherein said flowable compositionfurther comprises an ingredient selected from the group consisting ofadhesion promoters, leveling agents, metal oxides, waxes, surfactants,photosensitizers, antifoaming agent, oxygen inhibition offsettingadditives, and mixtures of the foregoing.
 16. The method of claim 1,wherein said surface is selected from the group consisting of bowlinglanes, vinyl composite tile, hardwood flooring, and laminate flooring.17. The method of claim 1, wherein said exposing is carried out with anLED light source.
 18. A protected surface, said surface comprising acured coating on said surface, said cured coating being formed from aflowable composition being selected from the group consisting of: (1) ametal oxide composition comprising: silica nanoparticles, aluminananoparticles, or both; an acrylate; and a photoinitiator; (2) a hybridcomposition comprising free radical polymerizable monomers, cationicpolymerizable monomers, and a photoinitiator; and (3) a polymericcomposition comprising a polymer and a photoinitiator dissolved ordispersed in a solvent system, said polymer being selected from thegroup consisting of epoxies, polyurethanes, acrylates, and mixturesthereof; said flowable composition having a viscosity of less than about200 cP and comprising less than about 5% by weight volatile organiccompounds.
 19. The protected surface of claim 18, wherein said flowablecomposition further comprises a source of thiols.
 20. The protectedsurface of claim 19, wherein said source of thiols is present at a levelof from about 1% by weight to about 10% by weight thiols, based upon thetotal weight of the flowable composition taken as 100% by weight. 21.The protected surface of claim 18, wherein said flowable composition isessentially free of thiols.
 22. The protected surface of claim 18,wherein said flowable composition comprises less than about 1% ofvolatile organic compounds.
 23. The protected surface of claim 18,wherein said coating, when subjected to an abrasion test, has a ΔHaze ofless than about
 30. 24. The protected surface of claim 18, wherein saidcoating has a coefficient of friction of less than about 0.8.
 25. Theprotected surface of claim 18, wherein said coating has an adhesion ofat least about 90%.
 26. The protected surface of claim 18, wherein saidcoating has an impact resistance of at least about 140 inch-lb.
 27. Aflowable composition useful for treating a surface, said flowablecomposition being selected from the group consisting of: (1) a metaloxide composition comprising: silica nanoparticles, aluminananoparticles, or both; an acrylate; and a photoinitiator; (2) a hybridcomposition comprising free radical polymerizable monomers, cationicpolymerizable monomers, and a photoinitiator; and (3) a polymericcomposition comprising a polymer and a photoinitiator dissolved ordispersed in a solvent system, said polymer being selected from thegroup consisting of epoxies, polyurethanes, acrylates, and mixturesthereof; said flowable composition having a viscosity of less than about200 cP, comprising less than about 5% by weight volatile organiccompounds, and being curable by light having a wavelength of from about320 nm to about 700 nm.
 28. The flowable composition of claim 27,wherein said flowable composition further comprises a source of thiols.29. The flowable composition of claim 28, wherein said source of thiolsis present at a level of from about 1% by weight to about 10% by weightthiols, based upon the total weight of the flowable composition taken as100% by weight.
 30. The flowable composition of claim 27, wherein saidflowable composition is essentially free of thiols.
 31. The flowablecomposition of claim 27, wherein said flowable composition comprisesless than about 1% of volatile organic compounds.
 32. The flowablecomposition of claim 27, wherein said acrylate is selected from thegroup consisting of acrylate esters, trimethylol propane triacrylate,1,6-hexanediol acrylate, 1,6-hexanediol diacrylate, isobornyl acrylate,hexafunctional urethane acrylate, hexafunctional epoxy acrylate,tripropylene glycol diacrylate, epoxy novolak acrylate, ethoxylatedtrimethylolpropane triacrylate, pentaerythritol triacrylate,dipentaerythritol pentaacrylate, melamine acrylate, propoxylatedneopentyl glycol diacrylate, and mixtures thereof.
 33. The flowablecomposition of claim 27, wherein said photoinitiator is selected fromthe group consisting of 2,4,6-trimethylbenzoyldiphenylphosphine oxide,bis(2,4,6-trimethylbenzoyl)-phenylphosphineoxide, 4-thiophenyl phenyldiphenyl sulfonium hexafluoroantimonate, and mixtures thereof.
 34. Theflowable composition of claim 27, wherein: said free radicalpolymerizable monomers are selected from the group consisting ofacrylates, methacrylates, other ethylenically unsaturated monomers andresins, and mixtures thereof; and said cationic polymerizable monomersare selected from the group consisting of epoxies, oxetanes, oxiranes,vinyl ethers, and mixture thereof.
 35. The flowable composition of claim27, wherein said flowable composition further comprises an ingredientselected from the group consisting of adhesion promoters, levelingagents, metal oxides, waxes, surfactants, photosensitizers, antifoamingagent, oxygen inhibition offsetting additives, and mixtures of theforegoing.
 36. The flowable composition of claim 27, wherein saidflowable composition is curable by an LED light source.